﻿
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace n_Modbus
{
	public static class Modbus
	{
		/// <summary>
		/// 【获取读数据报文，返回报文帧】
		/// </summary>
		/// <param name="myaddr">地址码</param>
		/// <param name="myfucd">功能码</param>
		/// <param name="reg_addr">寄存器地址</param>
		/// <param name="data_len">寄存器个数</param>
		/// <param name="myframe_len">报文长度</param>
		/// <returns></returns>
		public static byte[] Get_MyFrame( byte myaddr, byte myfucd, ushort reg_addr, ushort data_len, int myframe_len )
		{
			//主机命令帧格式
			//  字节    功能描述            例子
			//  1         地址码             0x01
			//  2         功能码             0x03
			//  3         寄存器地址高       0x00
			//  4         寄存器地址低       0x00
			//  5         寄存器个数高       0x00
			//  6         寄存器个数低       0x02
			//  7         CRC检验码低        0xC4
			//  8         CRC校验码高        0x0B
			ushort crc;
			byte[] message = new byte[8];
			//设置模块号
			message[0] = myaddr;
			//设置命令字
			message[1] = myfucd;
			//设置寄存器开始地址
			message[2] = WORD_HI( reg_addr );
			message[3] = WORD_LO( reg_addr );
			//设置寄存器数据长度
			message[4] = WORD_HI( data_len );
			message[5] = WORD_LO( data_len );
			//设置 CRC
			crc = CRC16( message, 0, myframe_len - 3 );
			message[6] = WORD_HI( crc );                 //CRC校验码高位
			message[7] = WORD_LO( crc );                 //CRC校验码低位
			return message;
		}
		
		/// <summary>
		/// 【格式化输出，校验读取的数据】
		/// </summary>
		/// <param name="readBuffer"></param>
		/// <returns></returns>
		public static string SetText( byte[] readBuffer, int Len )
		{
			//将byte 转换成string 用于显示
			ushort crc = CRC16( readBuffer, 0, Len - 3 );
			//crc校验
			byte hi = WORD_HI(crc);
			byte lo = WORD_LO(crc);
			if( (readBuffer[Len - 2] == hi) && (readBuffer[Len - 1] == lo) ) {
				return ToHexString( readBuffer, Len ) + "\nCRC校验正确: H-" + hi + " L-" + lo;
			}
			else {
				return ToHexString( readBuffer, Len ) + "\nCRC校验错误: H-" + hi + " L-" + lo;
			}
		}
		
		/// <summary>
		/// 【获取大写字母】
		/// </summary>
		/// <param name="bytes"></param>
		/// <returns></returns>
		public static string ToHexString( byte[] bytes, int len ) // 0xae00cf => "AE00CF "
		{
			string hexString = string.Empty;
			if( bytes != null ) {
				StringBuilder strB = new StringBuilder();
				for( int i = 0; i < len; i++ ) {
					strB.Append( bytes[i].ToString("X2") + " " );
				}
				hexString = strB.ToString().Trim( ' ' );
			}
			return hexString;
		}
		
		//================================================================================
		
		//【获取低位字节】
		public static byte WORD_LO(ushort crcCLo)
		{
			crcCLo = (ushort)(crcCLo & 0X00FF);
			return (byte)crcCLo;
		}
		
		//【获取高位字节】
		public static byte WORD_HI(ushort crcHI)
		{
			crcHI = (ushort)(crcHI >> 8 & 0X00FF);
			return (byte)crcHI;
		}
		
		//================================================================================
		
		/// 【CRC校验】
		/// 
		/// </summary>
		/// <param name="buffer">报文帧合适前6字节</param>
		/// <param name="Sset">开始位</param>
		/// <param name="Eset">结束位</param>
		/// <returns>CRC校验码</returns>
		public static ushort CRC16(Byte[] buffer, int Sset, int Eset)
		{
			byte crcHi = 0xff;  // 高位初始化
			byte crcLo = 0xff;  // 低位初始化
			for (int i = Sset; i <= Eset; i++) {
				int crcIndex = crcHi ^ buffer[i]; //查找crc表值
				
				crcHi = (byte)(crcLo ^ _auchCRCHi[crcIndex]);
				crcLo = _auchCRCLo[crcIndex];
			}
			return (ushort)(crcHi << 8 | crcLo);
		}
		
		//#region CRC高位表 byte[] _auchCRCHi
		private static readonly byte[] _auchCRCHi = new byte[]//crc高位表
		{
			0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
			0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
			0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
			0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
			0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
			0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
			0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
			0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
			0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
			0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
			0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
			0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
			0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
			0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
			0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
			0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
			0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
			0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
			0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
			0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
			0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
			0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
			0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
			0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
			0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
			0x80, 0x41, 0x00, 0xC1, 0x81, 0x40
		};
		//#endregion
		
		//#region CRC低位表 byte[] _auchCRCLo
		private static readonly byte[] _auchCRCLo = new byte[]//crc低位表
		{
			0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06,
			0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD,
			0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09,
			0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A,
			0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4,
			0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
			0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3,
			0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4,
			0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A,
			0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29,
			0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED,
			0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
			0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60,
			0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67,
			0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F,
			0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68,
			0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E,
			0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
			0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71,
			0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92,
			0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C,
			0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B,
			0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B,
			0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
			0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42,
			0x43, 0x83, 0x41, 0x81, 0x80, 0x40
		};
		//#endregion
	}
}
